A main or mizzen sail on a sailboat is customarily secured to or wound around its boom when not in use and protected by a sail cover. A jib or fore staysail is either stored by winding it around its stay or stuffing it into a sailbag after its hanks have been unsnapped from its stay.
Furling the jib around the jibstay is only possible when complicated and failure-prone gear is provided at the ends of the stay. Thus the commonest procedure is to unhook the jib when it is to be stored and stuff it into a sailbag which itself is stowed in the cabin when not in use or tied down to the deck or bowsprit. Tucking the sail into the usually cylindrical bag is troublesome and time consuming. Furthermore the bag must be secured to a support--the bowsprit for a flying jib or the deck for a working jib--with its jib inside, or the entire sail must be removed and stowed in the bag below decks.
When the jib is to be used again after storage in a conventional sailbag it is necessary, after fetching the bagged jib from below, to pull the jib out of the bag, attach the head to the jib halyard, secure the hanks to the jibstay, and attach the tack to the appropriate eye on the deck or bowsprit when the sail has been removed altogether to keep the ungainly sailbag out of the way.
This procedure is complicated and frequently takes up valuable time at the start of a sail. Furthermore the stowed jib is unsightly when left on deck and inconveniently out-of-the-way when stowed below.